1. Field of the Invention
This invention relates in general to a tool for opening cans and more particularly to a new and improved opener tool which facilitates opening of cans having self contained opening systems.
2. Description of the Prior Art
For some time now cans, particularly those used in the beverage containing arts, have been provided with user actuated self contained opening systems in the tops thereof to permit the can to be opened without the necessity of employing a conventional opener.
The first type of opening system to achieve wide usage was that commonly referred to as the "Pull-ring" opening system. Briefly, this type of opening system includes a pull-ring which is riveted or otherwise affixed to a scored tear-away closure provided in the top, or lid, of the can. When opening such cans, the user grasps the pull-ring and tears away both the pull-ring and the scored closure, thus forming an access opening in the top of the can. In that the pull-rings are relatively small and the edges of the tear-away closure are very sharp, it is not uncommon for a user to be cut when opening such a can. Although the tear-away effort exerted by a person opening a can of this type is relatively small, sore fingers, broken fingernails, as well as the above mentioned cuts, can result particularly when an individual must open a plurality of such cans, as often occurs, for example, in commercial establishments, and the like. As a result of this, several devices, or tools, have been proposed for use in opening the pull-ring type of cans, with such tools being used in place of a person's fingers. Examples of such openers are fully disclosed in U.S. Pat. Nos.: 3,459,075; 3,460,411; 3,656,375; 4,120,216; and 4,133,228. To the best of my knowledge, none of these opening tools disclosed in these patents have achieved any degree of commercial success.
In addition to the above stated problems, the tear-away pull-ring closure systems have resulted in several other problems which have caused them to fall into disfavor to the extent that some states have passed statutes against their use. The tear-away pull-ring closures are a discardable item and they are causing considerable litter problems, cut feet at beaches, and they have killed many fish in lakes and streams. Some very serious medical problems have resulted due to some users dropping the pull-ring closures into the opened cans and swallowing them during subsequent drinking of the beverages contained in the cans.
As a result of all of these problems and the increasing ban being placed on the tear-away pull-ring closure systems, a newer opening system has been developed which may be referred to as a "Stay-on-tab" opening system. It is contemplated that this newer can opening system will eventually completely replace the tear-away opening systems but this has not fully occurred as yet.
The stay-on-tab opening systems generally include a tab structure which is permanently affixed to the top, or lid of the can, such as by means of a rivet. The tab structure includes an elongated lever end portion and a relatively shorter opener end portion, and a tongue portion by which the tab structure is attached to the rivet. The tab structure is configured so that lifting of the lever end will cause the tab structure to pivotably move about the rivet to move the opener end downwardly toward the surface of the can's lid. Such downward pivotable movement of the opener end of the tab brings it into bearing engagement with a partially scored closure provided in the lid of the can with the result being the breaking of the scored portion of the closure with deformed displacement thereof inwardly into the interior of the can. In this manner, both the tab structure and the deformably displaced closure remain attached to the can with the closure being disposed where it cannot cut a user or cause other problems.
In stay-on-tab can opening systems prior to use, the lever end of the tab structure is disposed in overlaying engagement with the surface of the can's lid, and in some cases is recessed within a depression formed in the lid. In either case, to open such a can, the user must use a fingernail to raise the lever end of the tab a distance which is sufficient to permit gripping thereof so that the opening operation can be completed. The effort required to initiate and complete such an opening operation, as was the case in the hereinbefore described tear-away opener systems, can break fingernails and hurt fingers particularly when a plurality of these cans are being opened. And, some people simply lack the strength needed to use the stay-on-tab opener system.
For these reasons, opener tools have been proposed for use in opening cans having the stay-on-tab opener systems.
One such opener tool is disclosed in U.S. Pat. No. 4,257,287, as including a tab lifting and pulling hook formed on one end of an elongated handle and having a downwardly extending leg which depresses the partially scored closure simultaneously with the force being applied to the tab by the hooked end of the opener.
Another prior art opener tool is disclosed in U.S. Pat. No. 4,373,246, as including an elongated handle with a socket-like structure formed on one end thereof. To use this tool, it is moved into an aligned position and slidingly moved so that the lever portion of the can's tab structure will enter into the socket-like structure a distance which is about half way between the rivet and the extending end of the lever portion. Then, a lifting movement, which is similar to the pivotable movement of the can's tab structure is used to open the can.
As is known, the cans, lids, partially scored closures, the tab structures and even the attaching rivets are all made from a very thin gage aluminum. Due to this, care must be taken to properly apply opening forces on such stay-on-tab opening systems. In the absence of properly applied forces, the tab structure can malfunction, in other words, become distorted or completely torn loose so that it is rendered incapable of completing the can opening operation. When this occurs, the user is stuck with a partially open can from which drinking is impossible, or at least difficult, as determined by the amount of opening which had been accomplished when the malfunction occurred. Further, a partially open can is dangerous to use, in that serious cuts can easily result. To overcome this, the user must find some sort of instrument, such as a screwdriver, which can be safely used to finish pushing the partially scored closure down into the can.
It has been determined that when a person uses his fingers only to open a can having a stay-on-tab opening system, the above described type of malfunction does not occur in most instances. However, due to the increased force applying capability of opener tools, such as the prior art structures discussed above, the malfunction rate can easily increase to unacceptable levels.
The first prior art opener tool described above is an inherently unstable device due to the downwardly extending leg serving as a fulcrum. The leg is pointed which makes it difficult to pull the tab structure in a straight arcuate movement path, and any tool wobble, or other deviation from a substantially straight arcuate tab movement path can cause opener malfunction. This same prior art opener tool can be made without the extending leg fulcrum and the tool is then used to simply pull the tab structure through its arcuate movement path. Such free hand pulling increases the chances of tool wobble, or other misdirected movement forces.
The second prior art opener tool discussed above is inherently more stable than the first prior art opener tool, in that it is resting on the rim of the can to be opened at the beginning of the opening operation and therefore is in the proper position at least at the start of the opening operation. This initial proper starting position in conjunction with a lifting action, rather than a pulling action as in the first prior art opener tool, decreases the chances of tool wobble or other misdirected forces which could cause movement path deviation. However, the lifting forces exerted by this second prior art device are applied approximately half way between the rivet and the extending end of the lever end of the tab structure. In that this second prior art opener inherently increases the leverage an amount which is significantly greater than that which can be applied by a person's fingers, the application of the lifting forces at the half way point on the lever end as described above can easily distort the tab structure to an extent where it is incapable of being used to complete the opening operation, or can completely tear away the tab structure prior to proper opening of the can.
Therefore, a need exists for a new and improved can opener which overcomes some of the problems and shortcomings of the prior art.